1. Field of the Invention
This invention broadly relates to an appliance that is secured to a tooth during the course of orthodontic treatment. More particularly, the present invention is directed to an orthodontic appliance having a compact, low profile such that the appliance lies close to the tooth surface.
2. Description of the Related Art
Orthodontia is a specialized field within the general subject area of dentistry. Orthodontic treatment involves movement of malpositioned teeth to correct locations along the dental arch. Orthodontic treatment can result in improved occlusion for the patient as well as a more pleasing aesthetic appearance.
One type of orthodontic treatment involves the use of a set of components that are collectively known as “braces”. In this type of treatment, small slotted devices known as brackets are secured to the patient's anterior, cuspid and bicuspid teeth. An archwire is received in the slots of the brackets and forms a track to guide movement of the teeth to desired positions.
Each end of an orthodontic archwire is often received in an enclosed elongated passageway of a small device known as buccal tube. Buccal tubes are connected to the patient's molar teeth. The enclosed passageway helps prevent the end of the archwire from contacting the patient's soft tissue in the oral cavity, which might otherwise lead to pain and injury. In some instances, buccal tubes are provided with a convertible cap along one side of the passageway that can be opened in order to convert the tube into a bracket when desired.
Orthodontic appliances such as brackets and buccal tubes typically include a base, a body extending outwardly from the base and support structure for connecting the appliance to the archwire. One type of base, known as a “direct bond” base, is adapted to secure the appliance directly to the enamel surface of a tooth by an adhesive. Another type of base, known as a “welding base”, is adapted to be welded to a metallic orthodontic band that encircles the patient's tooth.
A variety of archwire support structures are also known. In the case of buccal tubes, the archwire support structure may be a cylindrical member having internal wall sections that define an enclosed archwire slot or passageway. Other types of buccal tubes have archwire support structure that comprises an elongated rectangular block with wall sections defining an archwire slot or passageway. Buccal tubes with convertible caps often have small wings known as tiewings that can be used to ligate the archwire to the buccal tube once the cap has been removed.
In the case of orthodontic brackets, the archwire support structure often includes wall sections that define three sides of the archwire slot while the fourth side is open for insertion of the archwire. In some instances, the wall sections are located between one or more pairs of tiewings. In other instances, the wall sections are located in the center of the bracket and offset from the tiewings. An example of the former construction is shown in U.S. Pat. No. 5,746,594, and an example of the latter construction is illustrated in U.S. Design Pat. No. 290,040.
Over the years, many attempts have been made to improve the aesthetic appearance of braces. To this end, manufacturers have reduced the size of the brackets so that they are more difficult to see when in place in the oral cavity. This reduction in size can also help increase patient comfort because it is less likely that the bracket will unduly impinge upon adjacent soft tissue.
A variety of low profile orthodontic appliances have been proposed in the past. In some appliances, manufacturers have reduced the overall depth of the bracket in a buccolabial direction (i.e., in a direction toward the patient's lips or cheeks) by reducing the size of the body located between the base of the appliance and the archwire support structure. Such construction results in the archwire support structure being located relatively close to the base.
In other instances, the manufacturers have eliminated the body that is conventionally located between the archwire support structure and the base. For example, one commercially available buccal tube appliance comprises an elongated, generally “U”-shaped structure resembling an inverted three-sided trough that is directly welded to a base. In this appliance, the buccolabial side of the base serves as the fourth wall for the archwire slot such that the archwire is surrounded on all four sides.
However, many of the low profile appliances known in the past are not considered satisfactory. For example, the appliance mentioned in the preceding paragraph is not entirely satisfactory because the buccolabial side of the base, including the portion of the base within the archwire slot, has a convex, curved configuration that matches the shape of the tooth. An archwire received in the archwire slot of this appliance may bear against the convex-shaped base along only a fraction of the length of the archwire slot. As a consequence, precise control over movement between the archwire and the appliance is difficult to attain and the teeth may not shift to desired positions.
As can be appreciated, there is a need in the art for an orthodontic appliance that has a relatively low profile, and yet provides reliable, precise control over movement of the associated teeth.